Veneer lathe



Sept. 13, 1932. R. c. M'OOR'E 1,877,013

VENEER LATHE Filed June 25, 1929 2 Sheets-Sheet 1 speed.

Fa' st S 94 4 sept- 1932- R. c. MOQRE 1,877,013

VENEER LATHE Filed Jufne 25. 1929 2 Sheets-Sheet 2 fie. 4

Arne/vans.

Patented Sept. 13, 1932 UNITED STATES ,ATNT .OFEIICEEIJ:

RICHARD o. Moonor rarnnsvrnin, onro, AssrGNon r "meson MANUFACTURING company, or: rnrnnsvrrnn, onro, a coeronnrron or onro, I

vnnnnn LATHE I Application filed ,Tune 25, 1929. Serial No. erases.

This invention relates to a veneer lath-e,

: and more particularly to the driving mechanism for the log spindles thereof and to the is cut from the rotating log more rapidly at first while the log diameter is relatively large,

than it is later after the log diameter has been diminished in size. In other words,

the veneer strip comes Off the outer circum-' ference of the log rapidly, but steadily diminishes in speed until when the core of the. log is reached'the veneer strip is produced very slowly.

The prlncipal object of the present invention is to provide a veneer lathe capable of cutting a veneer strip froma log at a constant I rest current motor as'the driving means for rate of production irrespective of the log diameter.

Another object is to provide the spindles will vary in a predetermined ratio to variations in the log dlameter.

veneer lathe means for automatically controlling the driving means forthe log spindles, so that the rate ofrotation of the log supported by the spindles will be accelerated in the proper proportion to the diminution of the diameter of the log as the veneer strip is cut therefrom.

Another object is to provide a drive'for'a veneer lathe, whereby the lathe will always produce veneer at constant speed, and one which may be instantaneously controlled ,ior.

quickstopping, quick reduction in speed. and

Additional objects and advantages Wi11bein a veneer lathe, means for automatically controlling the driving means for the log spindles, so that the rate of rotation of the logsupported bycomeapparent hereinafter, as the description 'of an embodiment of the inventi'onproceeds.

Inaccomplishing the above objects the inventi'omim its broader aspects, contemplates the provision, in a veneer lathe, of means for automatically increasing in the proper ratio or amount'the speedof rotation of the logas the diameter thereof decreases, whereby ;the veneer strip will be cut always at a constant rate,' irrespective of log diameter, and-to em ploy as a driving means for the-log spindles which support the log and effect its rotation, a driving element having a constant operating speed, irrespective of load, and capable of being controlled 'for'quick stopping, quick deceleration, and quick acceleration for rounding up the log when necessary.

M orefspecifically, the invention contem plates the employment of a shunt wound dithe log spindles, and the control ofthe speed in diameter of the log supported by the spindles, o

Before proceeding with the detailed de- A more Specific Object is to provide in j scription of a particularembodiinentofthe invention, and in orderthat the advantages inherent in the present inventlon Wlll be apparent at once, it will be advisable to set.

forth briefly the attempts which have been .made heretofore to controlthe operation. of

the: driving means for the log spindles with view of obtaining I a constant. cutting rate for the, veneer strip irrespective oflog diam- "iter variatlons.

Amongthe diflt'erent-attempts to'obtain this result, the oldest was theemployment of the double clutch pulley, which provided two distinct speeds of rotation for the log. The low speed was used on large logs, and: the high speed on timber of smaller size. (Subsequently, an individual steam engine drive was used where the speed of the lathewas controlled by a throttle operated by the cutter, and still later the slip ringrmotorwas introduced, while at the present time thereare-a number of lathes operating with-Reeves variable speed transmissions .forproviding speed control of the log. The double clutch pulley drive is not much better than the ordinary constant speed drive and, therefore, has not been followed to any extent in actual practice. The steam engine drive possesses a number of disadvantages in that it is difficult to get an engine which will start and stop as rapidly as it should in order to provide maximum production, while in addition, this type of drive requires a large amount of space which is often not available. The slip ring motor provides a speed range of 2 to 1, but since this type of motor has the same operating characteristics as the direct current series wound motor, namely, the speed of operation at any time depends entirely upon the load, the result is that in order to approximate a constant cutting speed it is necessary to continually adjust the speed control. The Reeves transmission provides a very good speed regulation, but owing to its design the cost of a proper transmission is excessive. Since the horse power required by a lathe running at constant cutting speed must essentially be constant horse power, the Reeves transmission is not suitable for use with veneer lathes, as such transmission is rated on a constant torque basis, namely, the horse power which it can transmit is proportional to the speed of the high speed shaft. It is,

' therefore, necessary in using a Reeves transmission toselect one which will provide the proper horse power at low speed, but it will be quite apparent that the same transmission running at high speed will be capable of handling four or five times this amount of power.

Another disadvantage of the Reeves transmission is that it does not respond readily if it is desired to change the speed quickly, and in order to stop a lathe equipped with such transmission it is necessary to use a may be varied by changing the field strength,

while at any given value of field strength the speed will remain constant regardless of the load. Furthermore, the motor can be so built that it will deliver the same horse power at anyspeed within the range for which it is designed, while in practice the field strength may be varied by introducing resistance into the shunt field circuit, with the result that as the resistance is increased the field current diminishes and the field strength decreases, causing the motor to run faster.

In order to more clearly bring out the ad vantages of the present invention than does the foregoing discussion, a specific embodiment of the invention will be described hereinafter, such embodiment being illustrated in the accompanying drawings wherein Fig. 1 is a transverse fragmentary section through a veneer lathe embodying the invention, the well-known parts of the lathe being shown diagrammatically.

Fig. 2 is a fragmentary rear view of the lathe showing one of the end frames.

Fig. 3 is a diagrammatic showing of the wiring circuit and controls of the lathe.

Fig. i is a top plan view of the lathe.

It is not thought necessary to set forth herein a complete description of the operative parts of the veneer lathe since the same are so well known in the art and may be found on a majority of veneer lathes in use at the present time. Therefore the showing in the drawings of the lathe will be more or less schematic, while the description will only go into detail sufficiently to illustrate the location and mode of application of the invention, it being understood that the invention may be applied to any type of veneer lathe and that so far as the present application relat-es to a specific form of lathe, it is simply by way of example.

The lathe comprises the usual end plates 10 together with a bed plate 11, which plates support the knife carriage mechanism and log supporting spindles, together with the driving connections for the same. As is understood, the log supporting spindlesare arranged adjacent the front side of the lathe one of such spindles being supported by each of the end plates 10 so that alog 12 may be supported by the spindles at its opposite ends and extend longitudinally of the lathe, it be ing understood that when the lathe is in operation the spindles rotate and, in turn, rotate the log.

The knife carriage comprises the knife bar 13 extending longitudinally of the lathe and supported at two places at its opposite ends.

The first point of support for the opposite ends of the knife bar 18 formed by its circular tongue and groove connection, indicated at l t by dotted lines, in the head block V which, in turn, is slidably mounted in a guideway 15 in the end plates. This form of mounting for the knife carriage is well understood in the art and further reference thereto or illustration thereof is unnecessary.

The other point of support for the opposite ends of the knife bar 18 is at the lower side thereof where the pin 16 is connected to a block 17 sliding in a slot 18 in a pitch-way frame 19.

trics arranged at opposite ends of the frame whereby the eccentrics may be moved to Although not illustrated herein W it is customary to support the pitch-way 77 the-spindles.

' stant rateor speed of production. The.

- newbie slot 18 -in: the frame should incline downwardly from the back of the lathe toward The knife the cutting-edge of theknife 20 is in. line with the centers ofthe circular tongue and grooveslt in thehead block, while the en--- tire knifeL-bar pivots about this. line during:

its feeding or receding -movements. It is to a shaft 22 whichisoperatively"associated with :the driving mechanism Lfor= the .lathe, whereby'when: the lathe isin operation ihe" movement of the feed screws21 will impart the feeding movement to the kni-feibar so as to-maintain the cutting edge of the knife in engagement with the leg as the latter is rotated bythe-spind'les and is accordingly reduced in diameter. 'The axial centers of-the feed screws 21 shoul d be in the same horizontal plane as the cuttingedge of the knife so the thrust thereof is put inline with the knifeandchatter, due to worn parts,'is eliminate'd;

From'the foregoing description, together with the well-known structural and operat ing characteristics of veneer lathes, it'should be understood that when the lathe is in operation the 10g spindles are rotated and, of.

course, the log supported thereby, while the knife bar head is fed toward the logand the cutting edge of the" knife maintained -in the propercutting position with respect-to the circumference of'the'log. Aspreviously explained, the ideal driving arrangement for -'a veneer lathe is one wh'erein'the rotative speed of "the log spindles and the log willbe proportionately increased as the diameter of the log decreases due'to the cutting of the veneer strip therefrom, so that the .knife 1 will cut a veneer strip from the log at a conreason for this is quite evident'w-hen it'is realized that the veneer-strip'will be cut from the log when the latteris of its-maximum ting rate when the log has been materially reduced in diameter. In order to provide for this ideal drive, the present invention the shunt wound direct current motor is that its speed may be varied by changing the field strength, it is proposed to introduce a resist- 155 ance into the shunt field circuit and to con-- decreases. is formed to support, preferably at therear head.

.tation ofthe wheel .25 and operating shaft diameter at a rate greatly exceeding the cutanism operatively associated'with the knife barhead and operated thereby as the head .movesin its feeding movementtomaintain bar should be so mountedthat'" the cutting edge of theknife in engagement with thelog as the diameter thereof reduces S nce the motor may be caused to run faster asthefield current and the'field strength dc:

creases, itwill thus be necessary to increase 5 i the resistancein the shunt field circuit in a understood that theknifebar headblocks are reaclroperatively connected with a:feedscrew 21, in turn connected through gearing-1 predetermined amount as the log diameter To this end one of the end plates side of the lathe, a suitable rheostat 24, such to as the conventional pancake rheostat, this rheostat being arranged in the shunt field circuit. 1 7

A wheel 25is mounted on the operating shaft 26 of therheostat so as to engage a suit able member such as the leather face rack 27 operatively associated with the knife'bar In operatively connecting the rack 27 to the knife bar head, a bar 28 supports the. rackbar 27 and is bolted to a filler block 29 '90 and to the knife bar head at one of its ends ZLHCl'lS slidably supported at its other end by means of a guide 30 carried by the frame of the lathe. It will thus be seen thatas theknife bar head moves forwardly as the log '95 diameter diminishes that the rack bar 27 will move in directiproportion with the movement of the knife bar head and will cause r o- 26*of the-rheostat, and, in turn, increase the resistance inthe shunt field circuit of the .dlfferent operatlng characteristics may be obtained' thereby, but in order to clarify the .195

invention and the mode of its operation a specific operating arrangement with respect to the rheostat and the drive for the lathe'will be set forth herein by way of example. Supposing thatit is, desired to provide a no constantcutting speed between log diameters of '28- maximumand 7 minimunr, the motor would be'designed to provide constant horse power'from 250 to 100GB. P. M. and:

would be so geared to thelog spindles that i the corresponding log-speeds would be 30 R. P. M. minimum and R". P. M. maximum; It'will be seen that when the knife is in-v position for cutting on a"28 diameterii circle orxlarger, the'spindles andthe'log would berevo'lvin'g at'30 R P. M. As the 'knife bar advances toward the spindlesthe -rack-27T'engagesthe wheel 25 andoperates the rheostat,which should be so designed as'-* to throw:resistanceintothe shuntwound cir- Jand=7 diameter. Thusit will b.e'seen=thatwhen the diameter is 28" and the spindles are rotating at R. P. M., the product will be 840, while after the log has been reduced to 21 in diameter and the rotation of the spindles accelerated to R. P. M. the product will still be 840. In the same way, when the diameter has been reduced to 14" and the speed of the spindles accelerated to R. P. M., or just twice the speed at 28 diameter, the product will still be 840. The speed of the log spindles may thus be increased or accelerated in this proportion until at 7 diameter, which is the minimum for the eX- ample given, the maximum speed of the spindles,'namely, 120 R. P. M., is reached.

It is understood that the above description applies to one particular case and that since motors with a speed variation of as much as 6 to 1 by field control, are available, it would be possible to provide constant cutting speed between 42 diameter maximum and 7 diameter minimum, or if larger logs are used the range with the 6 to 1 motor could be made 48 maximum to 8 minimum or 54" maximum to 9" minimum, and so on.

In addition to the foregoing desirable manner of providing constant cutting speed for the veneer strips, it is possible by using the shunt wound direct current motor to have the entire control of the motor through push buttons, by means of automatic starting equipment. The control push buttons are shown in Fig. 3 at 31 and 32 together with the circuits therefor, but since any conventional automatic starting equipment may be used in the circuit, the acceleration current relays, overload protection devices and the like, are not shown. Since defects occur in the logs such as wind-shakes, knots and the like, it is necessary at'certain times to reduce the speed of the log to a minimum, and for this purpose a push button 38 is provided which may close a circuit shunting around the rheostat resistance and throwing full field on the motor, thus causing the latter to run at its slowest speed. It is often necessary in rounding up a rough log to cause the log to revolve at any predetermined speed within the limits of the motor and a suitable switch 3% is pro vided for this purpose; thus if the circuit were designed to cause the log to revolve at 60 R. P. M. for rounding up, the moment the switch was released the driving motor would automatically assume a speed correspond ing to the cutting speed for which the equipment is designed. In order to stop the lathe practically instantaneously, a dynamic brake 35 011 the motor may be thrown by depressing the stop button 32.

It should be understood that the invention is susceptible in its broad aspects of being used with various types of lathes in different modes of application and that the embodiment herein shown, together with the specific wiring circuit, is merely by way of illustration and that the invention is to be limited thereto only so far as the scope of the claims so limits it.

Having thus described my invention, I claim:

1. In a veneer lathe, rotatable spindles adapted to support a log, a motor for operating said spindles, means for cutting veneer strips from said log and automatically ads. justable to compensate for variations in the diameter of the log, and means forautomatically controlling the speed of operation of said motor, said means including a'rheostat in the motor circuit and having an operating. shaft provided with a wheel, and a'rack' bar connected to said cutting means and engaging said wheel.

2. In a veneer lathe, rotatable spindles adapted to support a log, a shunt wound diirect current motor for operating said spindles, means for cutting veneer strips from said log and automatically adjustable to compensate for variations in the diameter of the log, and means for automatically ac celerating the speed of operation of said motor in proportion to the diminution of the diameter of the log, said means including a rheostat arranged in the shunt field circuit of the motor and having anoperating shaft 1 provided with a wheel, and a rack bar operatively engaging said wheel and connected to said cutting means to move therewith.

3. In a veneer lathe, rotatable spindles adapted to support a log, a driving means for said spindles having a constant operating speed irrespective of load, means for cutting veneer strips from the log and automatically adjustable to compensate for variations in the log diameter, means operatively associated with said last named means for automatically accelerating the speed of operation of the driving, and means operable independently of or in conjunction with said last named means for quickly decelerating or ac celerating the speed of operation of-said driving means. i

In testimony whereof, I hereunto aflix my signature.

RICHARD O. MOORE. 

